Various motorized two-wheeled toys have been described in the prior art, such as the radio-controlled motorcycle-like vehicle toy of Asano (U.S. Pat. No. 4,966,569) or the two-wheeled motorized toy of Wagstaff (U.S. Pat. No. 4,897,070). Such toys prevent tipping in a fore/aft direction either by placing the wheels in rotation about axes which are parallel and disposed one ahead of the other (as in a bicycle or scooter) or by placing the center of gravity (CG) of the chassis beneath the axis of rotation of the wheels (as in Wagstaff) so that no overturning torque may be developed. Stability with respect to lateral tipping of the in-line-wheel toys is maintained by virtue of rolling of the wheels about substantially horizontal axes, in accordance with well-known physical principles. Such operation can avail to maintain fore/aft stability of a toy vehicle only if points of contact between the toy and the underlying surface are separated along a direction parallel to the motion of the toy, i.e., the wheels are “in-line.”
Toys are also known in which the toys are directly stabilized by mechanical action of a gyroscope. The “R/C UFO Buddies” currently sold by FAO Schwarz are examples of such toys.